Sprinkler irrigation has over the years replaced many other forms of irrigation methods because it minimizes erosion, prevents many drainage problems, does not require land leveling, and provides light applications of moisture for "irrigating up" crops.
Whenever a sprinkler system is referred to by name, the reference is usually made to the manufacturer's brand name. Sprinkler systems are typically classified by the degree of their portability. For example, a fully portable system can be moved from one field to another, a semi-portable system is similar but the pumping plant is in a fixed location. There are also semi-permanent, fully permanent and hand-moved systems.
A number of manufacturers currently provide fittings for sprinkler systems. These fittings included couplers, ells, Tees, reducers, Tee-type valves for maintaining hydrants, and valve-opener elbows. Such fittings typically appear every 20 to 40 feet along portable sprinkler laterals and, therefore, are the fittings by which you can recognize the make of a system easily.
In some respects, the couplers, as well as other fittings, are much alike. All have either one or two replaceable rubber gaskets to prevent the loss of water between the pipe and the coupler when pressure is applied. Nearly all of these gaskets are made to permit water to drain out whenever the line is shut off and the pressure is released.
There are some differences in the way the couplers of different manufactures fasten to a pipe. Some have a latch on both ends, others are bolted or welded to the pipe on one end and still others have one end rolled or pressed into the pipe. On most systems, the coupler makes a flexible joint which allows the sprinkler pipe to bend or form an angle. Some flexibility is desirable, particularly on rolling land.
Most couplers also have a guide or guard apron that helps to keep dirt from being scooped up when the pipe is inserted, or moved.
Current use of aluminum pipe couplers for sprinkler lines has settled out to 3 popular styles, the "drop lock" or "no-latch" style and the "tow line" or "drag line" style. These fittings are fitted with one of two styles of Chevron gaskets: a "drain" gasket which at a drop in pressure is designed to leak water through the coupler and a "non drain" gasket which leaks water at a substantially lower pressure. The locking mechanism for the three styles is a latch or band bolted or welded to the opposite (or male) end of a piece of aluminum tubing. Sprinkler pipe fittings are cast aluminum or steel galvanized. There are several manufacturers of these fittings, the basic styles have been used from before 1970. This coupler is fitted with a 3/4" or 1" Female iron pipe thread to facilitate the installation of a metal (usually steel galvanized) riser of 6-36" lengths and a sprinkler of varying sizes and manufacture.
This sprinkler-riser-coupler-aluminum tubing combination, is light in weight and is commonly referred to as "hand move" pipe, installed and removed manually, typically by three individuals. The "drag line" or "tow line" styles can be pulled by tractor or machinery but it is necessary to install manually and disassemble manually by two or more individuals. "Hand move" aluminum pipe has, in recent years, been adapted to a system generally referred to as "solid set" or in a complete grid covering an entire field. These systems are laid out and removed manually typically by two laborers and one individual driving a farm style tractor and small trailer. Installation, removal, transport and storage of these pipe-coupler-riser-sprinkler assemblies commonly referred to as "hand move" pipe is cumbersome and labor intensive. The nature and advantage of the "hand move" aspect of the pipe and fittings is a distinct disadvantage in a "solid set" situation as the system requires constant monitoring in that couplers can come apart from wind, temperature changes, line surges, pipe misalignment, faulty latches, inadvertent labor or mechanical contact, slippage, and "riser flop". The gasket, designed to leak, to accommodate rapid "hand movement" is a distinct disadvantage to water conservation and inundation of localized water around couplers (promotes disease) and requires that entire pipelines be refilled prior to pressurization leading to line surges and air entrapment, both of which affect the integrity and safety of the system. The nature, rigidity and length (30-40') of "hand move" pipe and the inherent ability of a single person to lift and manipulate the assembly has been hazardous or fatal when laborers make inadvertent contact with electrical sources such as power lines, boxes and outlets.